Hint : Vocal cords also known as vocal folds are voice reeds are folds of tissue in the throat that are key in creating sound throw localisation.
Complete Solution:- Vocal cords are stretched flaps of skin in your throat that vibrate to make a sound. When we speak, the air parts our vocal cord which makes them vibrate. Therefore, the part that vibrates when we speak is the vocal cord. Which changes the sound we made by stretching and contracting the muscle attached to our vocal cords. When we speak, we use the muscle in our tongue lips, jaw to make the vocal cord vibration into words. The larynx is a major source of sound in speech generating sound through the rhythmic opening and closing of vocal folds. To oscillate, the vocal folds are drought near enough together such that their pressure builds up beneath the larynx. The fold is post apart by this increased subglottal pressure with the inferior part of each fold leading the superior part. Such a wave-like motion causes a transfer of energy from airflow to the folded tissues. Under the correct condition, the energy transferred to the tissue is large enough to overcome losses by dissipation and oscillation pattern which sustain itself. In essence sound is generated in the larynx while chopping up a steady flow of air into the little puff of sound wave. The perceived pitch of a person voice is determined by the number of different factors, most importantly the fundamental frequency of the sound generated by the larynx
Additional information:- The true vocal cords are distinguished from the false vocal fold known as vestibular fold which sits slightly superior to more delicate true folds. These have a minimal role in normal phonation, but can produce deep Sonorous tones, screams and growls. The fundamental frequency is influenced by the length, size and tension of vocal fold. The visor elastic property of human vocal fold lamina properties are essential for their vibration, and depends on the composition and structure. Other studies suggest that hormones also play an important role in vocal fold maturation. There is a steady increase in the elastin content of the lamina propria of human age resulting in a decrease in the ability of lamina propria to expand caused by cross branching of the elastin fiber. Among other things this leads to the mature voice being better suited to a Rigor of Opera. Any injury to human vocal fold elicits a wound healing process characterized by disorganized collagen deposition and eventually formation of Clear tissue. Revise pathology called Reinke Edina, swelling due to abnormal accumulation of fluid occurs in the superficial lamina propria and Reinkis space. This causes the vocal cord mucosa to appear floppy with excessive moment of cover that has been described as looking like a loose sock. The great mass of vocal fall due to increased fluid lowers the fundamental frequency during phonation.
Note:- The length of the vocal fold at birth is approximately 6 to 8 millimeter and grows to its adult length of 8 to 16 millimeter by adolescence. Males and females have different vocal fold sizes. Adult male voices are usually lower pictures due to longer and thicker folds. The male vocal cords have folded between 1.75 cm & 2.5 cm in length, while female vocal cords have folded between 1.25 cm and 1.75 cm in length. The vocal fold of children are much shorter than those of adult males and females. The difference in vocal fold length and thickness between male and female causes a difference in vocal pitch. The vocal fold generate a sound rich in harmonics .Harmonics are produced by collision of the vocal fold with themselves by recirculation of some of the year back through the trachea or both singer can isolate some of those harmonious in a way that is perceived as singing in more than one page at the same time. A technique called overtone singing